Conventionally, a liquid crystal display device is provided with a device called a backlight (hereinafter, referred to as the “backlight device”) which uses a Cold Cathode Fluorescent Lamp (CCFL) or the like as a light source. For the backlight device, there are one called a “direct type” in which a plurality of light sources are arranged side by side on the back side of a display portion, and one called an “edge light type” in which a light source is arranged at one end of the display portion. In the direct type backlight device, luminance can be easily increased but since a plurality of light sources are used, luminance non-uniformity easily occurs. On the other hand, in the edge light type backlight device, a reduction in thickness can be easily achieved but it is difficult to increase the luminance.
Meanwhile, there is a direct type backlight device that adopts pseudo U-shaped lamps, each of which has two series-connected straight-tube type lamps arranged in a U shape. FIG. 7 is a block diagram showing a configuration of a conventional backlight device that adopts pseudo U-shaped lamps. The backlight device is configured by a pseudo U-shaped lamp 11 and an inverter board 12 having formed thereon circuits and the like for driving the lamp 11. The pseudo U-shaped lamp 11 is configured by a first lamp 111, a second lamp 112, and a conductor 113 that connects the lamps 111 and 112. The inverter board 12 includes a control circuit 130 and a lamp drive circuit 140. The lamp drive circuit 140 includes a first and a second transformer 141 and 142 for applying an alternating voltage to the first and second lamps 111 and 112, respectively; a switching circuit 143 that supplies a voltage to primary sides of the respective first and second transformers 141 and 142; a first and a second rectifier circuit 144 and 145 for respectively half-wave rectifying currents flowing through secondary sides of the respective first and second transformers 141 and 142; and a stabilizing circuit 146 that combines and smoothes the currents having been half-wave rectified by the first and second rectifier circuits 144 and 145. Note that although a backlight device is generally provided with a plurality of pseudo U-shaped lamps 11, FIG. 7 only shows one pseudo U-shaped lamp 11 and the lamp drive circuit 140 for driving the lamp 11 for convenience.
In such a backlight device as described above, by the switching circuit 143 performing a switching operation by control performed by the control circuit 130, alternating voltages are generated on the secondary sides of the respective first and second transformers 141 and 142. Accordingly, the first and second lamps 111 and 112 emit light. At this time, the currents flowing through the secondary sides of the respective first and second transformers 141 and 142 are respectively half-wave rectified by the first and second rectifier circuits 144 and 145 and the half-wave rectified currents are combined and smoothed by the stabilizing circuit 146. Then, based on the value of the smoothed current, the control circuit 130 controls the operation of the switching circuit 143. With such feedback control, stable currents are supplied to the first and second lamps 111 and 112.
Note that Japanese Unexamined Patent Publication No. 2002-231034 discloses an example of the configuration of a backlight device such as that described above.    [Patent Document 1] Japanese Unexamined Patent Publication No. 2002-231034